10 ideas
| 11193 | Understanding begins with the notion of being and essence [Avicenna] |
| Full Idea: Understanding begins with the notion of being and essence. | |
| From: Avicenna (Abu Ibn Sina) (Commentary on the Metaphysics [1022], 1/6), quoted by Thomas Aquinas - De Ente et Essentia (Being and Essence) p.91 | |
| A reaction: I think I might put it that wisdom is only really possible for people who aim to grasp being and essence in some way. I see no prospect of understanding 'being', and even essences may be forever just beyond our grasp. |
| 21566 | 'Propositional functions' are ambiguous until the variable is given a value [Russell] |
| Full Idea: By a 'propositional function' I mean something which contains a variable x, and expresses a proposition as soon as a value is assigned to x. That is to say, it differs from a proposition solely by the fact that it is ambiguous. | |
| From: Bertrand Russell (The Theory of Logical Types [1910], p.216) | |
| A reaction: This is Frege's notion of a 'concept', as an assertion of a predicate which still lacks a subject. |
| 21567 | 'All judgements made by Epimenedes are true' needs the judgements to be of the same type [Russell] |
| Full Idea: Such a proposition as 'all the judgements made by Epimenedes are true' will only be prima facie capable of truth if all his judgements are of the same order. | |
| From: Bertrand Russell (The Theory of Logical Types [1910], p.227) | |
| A reaction: This is an attempt to use his theory of types to solve the Liar. Tarski's invocation of a meta-language is clearly in the same territory. |
| 23457 | Type theory cannot identify features across levels (because such predicates break the rules) [Morris,M on Russell] |
| Full Idea: Russell's theory of types meant that features common to different levels of the hierarchy became uncapturable (since any attempt to capture them would involve a predicate which disobeyed the hierarchy restrictions). | |
| From: comment on Bertrand Russell (The Theory of Logical Types [1910]) by Michael Morris - Guidebook to Wittgenstein's Tractatus 2H | |
| A reaction: I'm not clear whether this is the main reason why type theory was abandoned. Ramsey was an important critic. |
| 21556 | Classes are defined by propositional functions, and functions are typed, with an axiom of reducibility [Russell, by Lackey] |
| Full Idea: In Russell's mature 1910 theory of types classes are defined in terms of propositional functions, and functions themselves are regimented by a ramified theory of types mitigated by the axiom of reducibility. | |
| From: report of Bertrand Russell (The Theory of Logical Types [1910]) by Douglas Lackey - Intros to Russell's 'Essays in Analysis' p.133 |
| 21568 | A one-variable function is only 'predicative' if it is one order above its arguments [Russell] |
| Full Idea: We will define a function of one variable as 'predicative' when it is of the next order above that of its arguments, i.e. of the lowest order compatible with its having an argument. | |
| From: Bertrand Russell (The Theory of Logical Types [1910], p.237) | |
| A reaction: 'Predicative' just means it produces a set. This is Russell's strict restriction on which functions are predicative. |
| 11209 | The simple's whatness is its very self [Avicenna] |
| Full Idea: The simple's whatness is its very self. | |
| From: Avicenna (Abu Ibn Sina) (Commentary on the Metaphysics [1022], 5.5), quoted by Thomas Aquinas - De Ente et Essentia (Being and Essence) p.103 | |
| A reaction: Aquinas endorses this Aristotelian view in Idea 11208. |
| 13128 | 'Ultimate sortals' cannot explain ontological categories [Westerhoff on Wiggins] |
| Full Idea: 'Ultimate sortals' are said to be non-subordinated, disjoint from one another, and uniquely paired with each object. Because of this, the ultimate sortal cannot be a satisfactory explication of the notion of an ontological category. | |
| From: comment on David Wiggins (Identity and Spatio-Temporal Continuity [1971], p.75) by Jan Westerhoff - Ontological Categories §26 | |
| A reaction: My strong intuitions are that Wiggins is plain wrong, and Westerhoff gives the most promising reasons for my intuition. The simplest point is that objects can obviously belong to more than one category. |
| 11204 | The ultimate material of things has the unity of total formlessness [Avicenna] |
| Full Idea: The ultimate material of things has the unity of total formlessness. | |
| From: Avicenna (Abu Ibn Sina) (Commentary on the Metaphysics [1022], 11/12.14), quoted by Thomas Aquinas - De Ente et Essentia (Being and Essence) | |
| A reaction: This remark is not invalidated by developments in modern particle physics. |
| 15036 | An essence can either be universal (in the mind) or singular (in concrete particulars) [Avicenna, by Panaccio] |
| Full Idea: Avicenna's 'indifference of essence' says the essence of certain things can become universal or singular, according to whether it is entertained by the mind (as a universal) or concretely exemplified as a singular thing. One essence can exist in two ways. | |
| From: report of Avicenna (Abu Ibn Sina) (Commentary on the Metaphysics [1022]) by Claude Panaccio - Medieval Problem of Universals 'Sources' | |
| A reaction: This would appear to be a form of nominalism, since in the concrete external world we only have particulars, and it is our mode of thinking (by abstraction?) that generates the universal aspect. I think this is probably right. |